The digital representation of media content combined with computing and networking technologies provides a powerful way to publish. According to this relatively new mode of publishing, networking technology permits the delivery of digitized media content over a network such as the Internet to end user client computers. Communication protocols define how the digitized media content is exchanged over the network. A media player runs on the end user client computer to allow the user to render the media content.
Digital rights management is a central issue in the on-line commercialization of digital media content data. Digital media content data can promise of video and audio data, images, documents, software and other forms of digital content.
The usual property of digital content is that the publisher (or re-seller) gives or sells the content to a client, but continues to restrict rights to use the content even after the content is under the sole physical control of the client. For instance, a publisher will typically retain copyright to a work so that the client cannot reproduce or publish the work without permission.
A publisher could also adjust pricing according to whether the client is allowed to make a persistent copy, or is just allowed to view the content on-line as it is delivered. These scenarios reveal a peculiar arrangement. The user that possesses the digital content data often does not have full rights to their use; instead, the provider retains at least some of the rights.
A variety of digital rights management systems and methods are known from the prior art which are used to enforce that usage of the content data by the client is within the scope of the license the user has obtained from the publisher.
U.S. Pat. No. 6,330,670 shows a digital rights management operating system which protects rights-managed data, such as downloaded content, from access by untrusted programs while the data is loaded into memory or on a page file as a result of the execution of a trusted application that accesses the memory. To protect the rights-managed data resident in memory, the digital rights management operating system refuses to load an untrusted program into memory while the trusted application is executing or removes the data from memory before loading the untrusted program. This way unauthorised copying of the rights-managed data can be prevented.
U.S. Patent applications 2002/0013772A1 and U.S. 2002/0108049A1 show further digital rights management systems.
Windows® Media Rights Manager® is an end-to-end digital rights management (DRM) system which is commercially available from Microsoft. This system offers content providers and retailers a flexible platform for the secure distribution of digital media files. It lets content providers deliver songs, videos, and other digital media content over the Internet in a protected, encrypted file format and it helps protect digital media (such as songs and videos) by packaging digital media files.
A packaged media file contains a version of a media file that has been encrypted and locked with a key. This packaged file is also bundled with additional information from the content provider. The result is a packaged media file that can only be played by a person who has obtained a license.
One of the problems of digital rights management is that different publishers and content providers use different digital rights management methods. A client device therefore needs to support multiple digital rights management methods to enable a user to obtain and render content data from publishers using different kinds of digital rights management methods.
Another problem related to prior art digital rights management systems is that no renewal of a license can be obtained when the client device is off-line. For example the user has purchased a license which enables him or her to play back the content data a fixed amount of times. When the user is travelling and no network connection is available he or she may use up the acquired license so that no more play back is possible. In this instance the user needs to wait until he or she can reconnect the client device to the network for renewal of the license.
The present invention therefore aims to provide an improved method for providing content data to a client as well as a corresponding computer program and computer system.